Resolution

#1

Curiosity question. Does the ability of Sense to find new devices based on the signature of the current and voltage of the device diminish if there is a large load operating. For instance if my air conditioner is operating at about 2 KW and a 60 watt light bulb turns on, can it be found if the air conditioner is NOT operating. Are the larger operating loads “Masking” the smaller loads. One member of the community offered to put the current transformer clams on individual branch circuits to “capture” the signature of any devices on the branch that may be smaller loads so that the “signature” could later be compared when larger loads are operating. I’m probably here asking about proprietary information, so here goes anyway. If the Analog to Digital converter in Sense is only 8 bits it can only distinguish between current values of about 0.78 amps, but if it is 16 bits then 3 milliamps is the smallest discrete current value.
Any discussion??? Thanks, Karin

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#2

Two data points Karin,

  • Here’s a teardown of the Sense - we know that they are using 14bit ADCs. I think the 200A max rating is RMS, the clamps have to measure roughly 290A peak-to-peak. That would be about 20mA resolution at max current, though I’m sure some of that accuracy might sacrificed for headroom and flexibility.
    http://whatnicklife.blogspot.com/2017/12/sense-energy-monitor-teardown-sampling.html

  • There has been some talk from Sense on this forum about “noisy devices” masking other device signatures, the example of a “noisy device” being a plasma TV - relatively large wattage and highly variable at a rapid frequency (remember, Sense currently looks for very short signatures time wise).

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#3

I agree based on my personal experiences. Our water heater is less regularly detected in the summer months, even though it’s on for an hour at 5am and 5pm every day. I noticed the mornings seemed to be more reliable…because the AC is less likely to be running in the morning, and outside of April-November, leading to more consistent detection in the morning and in the winter :slight_smile:

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#4

That’s an interesting point. I’m also in AZ and my water heater is detected ~50% of the time now that it’s summer. Winter months gave a much truer reading.

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